WO2011083773A1

WO2011083773A1 - Multi-carrier modulated signal receiving device and integrated circuit

Info

Publication number: WO2011083773A1
Application number: PCT/JP2011/000057
Authority: WO
Inventors: 友彦谷口; 誠關藤
Original assignee: パナソニック株式会社
Priority date: 2010-01-07
Filing date: 2011-01-07
Publication date: 2011-07-14

Abstract

A signal is received by an antenna unit, and processes that are normally carried out upon a receiving device, quadrature detection processing, FFT processing, equalization processing, de-interleaving processing, de-mapping processing, decoding processing, energy despreading processing, Reed-Solomon decoding processing, are carried out. The signal that is inputted into the de-mapping processing unit (the post-equalization symbol point) is retained separately, and re-coding processing is carried out once more upon the data sequence of the result of the Reed-Solomon decoding in the same sequence as the modulation processing upon the transmitting device. Energy spreading processing, convolutional code processing, and mapping processing are carried out at time thereof.

Description

Multi-carrier modulation signal receiving apparatus and integrated circuit

The present invention relates to a technique for detecting an interference signal superimposed on a reception signal and removing the influence of the interference signal from the reception signal when receiving a multi-carrier modulated signal.

In recent years, terrestrial digital broadcasting has started in various countries around the world, and replacement with conventional analog television broadcasting is being promoted. The European terrestrial digital broadcasting standard (DVB-T) and the Japanese terrestrial digital broadcasting standard (ISDB-T) employ an OFDM (Orthogonal Frequency Division Multiplexing) system, and use a large number of carriers. A signal with a high transmission capacity can be transmitted.

In the OFDM system, a mechanism to prevent interference from preceding and following symbols called guard intervals makes it less susceptible to interference from reflected waves, or converts the transmission signal to a digital code and performs error correction code processing. As a result, the noise resistance of the received signal is improved. In particular, the ISDB-T standard introduces a data rearrangement called interleaving and a mechanism called hierarchical transmission that transmits a plurality of broadcasts with different noise immunity and selectively views them on the viewer side. Even when it drops, it is possible to view stable broadcasts. The above error correction code processing is an example, and various other signal processing techniques are incorporated, and by performing appropriate processing in the receiving device, it is normal even if there is a decrease in received signal level or radio wave interference. It is possible to keep the reception state.

Here, the configuration of a multicarrier modulation signal receiving apparatus for receiving ISDB-T broadcasting, which is a Japanese terrestrial digital broadcasting standard, will be described with reference to FIG. The multicarrier modulation signal receiving apparatus includes an antenna unit 601, a tuner unit 602, an A / D conversion processing unit 603, an orthogonal detection processing unit 611, an FFT processing unit 612, a TMCC decoding processing unit 613, and an equalization process. Unit 614, deinterleave processing unit 621, demapping processing unit 622, bit deinterleaving processing unit 631, decoding processing unit 632, energy despreading processing unit 634, and RS (Reed-Solomon) decoding processing unit 635. A TS (transport stream) reproduction processing unit 671, a TS decoding processing unit 672, and an MPEG (Moving Picture Experts Group) decoding processing unit 673.

The tuner unit 602 selects a signal in a predetermined frequency band from the signal received by the antenna unit 601 and outputs it to the A / D conversion processing unit 603. The A / D conversion processing unit 603 samples the OFDM signal output from the tuner unit 602, converts it to a digital signal, and outputs the digital signal to the quadrature detection processing unit 611.

The quadrature detection processing unit 611 multiplies the OFDM signal obtained from the A / D conversion processing unit 603 by a sine wave signal having the same frequency as that of the reference carrier wave, converts the signal into a baseband OFDM signal, and outputs it to the FFT processing unit 612. To do.

The FFT processing unit 612 extracts a signal sequence of an effective symbol period from the baseband OFDM signal output from the quadrature detection processing unit 611. Then, the FFT processing unit 612 performs discrete Fourier transform on the extracted signal sequence, generates a complex signal, and converts the complex signal obtained by the discrete Fourier transform to the TMCC decoding processing unit 613 and the equalization processing unit 614. Output.

The TMCC decoding processing unit 613 obtains a complex signal from the FFT processing unit 612. Complex signals obtained from the FFT processing unit 112 exist in the number of FFT points, and each of them is OFDM symbol data. For example, according to an operation standard called mode 3 of the ISDB-T broadcasting standard, the number of FFT points is 8192, and 8192 complex signals are obtained. Of these, 5617 are signals to be processed and are called OFDM symbols. The OFDM symbol data is arranged on a plurality of carriers defined in each of mode 1 to mode 3, and includes a TMCC (Transmission and Multiplexing Configuration Control) signal for transmitting control information. The TMCC signal is information that assists the demodulation and decoding operations of the receiver, such as system identification, transmission parameter switching index, emergency warning broadcast activation flag, current information, and next information. Among these, the transmission parameter information of the received signal includes the presence / absence of the partial reception layer, the number of segments for each layer, the time interleave length, the carrier modulation scheme, and the coding rate of the inner code (convolutional code in the ISDB-T standard). The carrier on which the TMCC signal is arranged is known on the receiving side, and the TMCC decoding processing unit 613 detects and extracts the TMCC signal from the OFDM symbol. Then, the TMCC decoding processing unit 613 performs demodulation processing corresponding to DBPSK (Difference Binary Phase Shift Keying) on the extracted TMCC signal in the time direction, and acquires control information transmitted by the TMCC signal from the result of the demodulation processing To do. The TMCC decoding processing unit 613 outputs the information included in the control information to the components that require the information for processing, although the output destination components are not explicitly shown in FIG.

In the ISDB-T standard, a plurality of layers having different transmission characteristics can be transmitted simultaneously, and the maximum number of layers is three. When the number of hierarchies is 2 or 3, the output of the deinterleave processing unit 621 is divided into hierarchies, and the demapping processing unit 622 to the energy despreading processing unit 634 perform processing for each hierarchy, and then the hierarchies are synthesized. The data is input to the RS decoding processing unit 635.

The equalization processing unit 614 receives a complex signal from the FFT processing unit 612. Complex signals obtained from the FFT processing unit 612 exist as many as the number of FFT points, and each of them is OFDM symbol data. For example, according to an operation standard called mode 3 of the ISDB-T broadcasting standard, the number of FFT points is 8192, and 8192 complex signals are obtained. Of these, 5617 are signals to be processed and are called OFDM symbols. The OFDM symbol data includes an SP (Scattered Pilot) signal every 12 carriers in the carrier direction. Further, the SP signals are arranged so as to be shifted by 3 carriers in the time direction. Therefore, the equalization processing unit 614 detects and extracts SP signals that are discretely arranged from the OFDM symbol.

Next, since the SP signal is a known signal, the equalization processing unit 614 divides the extracted SP signal by a known complex signal value to thereby determine a transmission path characteristic (SP signal) between transmission and reception of the SP signal position. Is estimated). The equalization processing unit 614 performs interpolation processing based on the estimated values of the transmission path characteristics of the SP signal positions discretely arranged in the OFDM signal, thereby transmitting the transmission path characteristics of each carrier between the SP signals. Is estimated. Then, the equalization processing unit 614 divides each OFDM symbol by the estimated transmission path characteristic of each carrier to obtain information on OFDM symbol points that compensate for the influence of the transmission path. The equalization processing unit 614 includes information on the OFDM symbol points (hereinafter referred to as “received OFDM symbol points”) compensated for the influence of the transmission channels, and transmission path characteristics corresponding to the “received OFDM symbol points”. The estimated complex signal is output to the deinterleave processing unit 621.

The deinterleave processing unit 621 sequentially receives the “received OFDM symbol point” and the data string of the estimation result of the transmission path characteristics from the equalization processing unit 614. Then, the deinterleave processing unit 621 rearranges the received “received OFDM symbol point” and the data string of the estimation result of the transmission path characteristics. The rearrangement rules are stipulated in the ISDB-T standard, and the deinterleave processing unit 621 performs a process of returning the signals rearranged randomly in the time direction and the frequency direction to the original order in the interleaving process on the transmission side. Do. Then, the deinterleave processing unit 621 outputs the “received OFDM symbol points” rearranged to the demapping processing unit 622 and the data string of the estimation result of the channel characteristics. However, the rearrangement in the time direction is performed according to the time interleave length of each segment included in the control information acquired by the TMCC decoding processing unit 613.

The demapping processing unit 622 obtains the “received OFDM symbol points” rearranged from the deinterleaving processing unit 621 and the data string of the estimation result of the transmission path characteristics. The OFDM symbol is mapped on the complex plane according to the carrier modulation scheme on the signal transmission side. For example, if the carrier modulation method is 64QAM, the signal is converted into one of 64 mapping points according to the obtained bit data.

Therefore, the demapping processing unit 622 regards the mapping point closest to the “received OFDM symbol point” as the transmission signal point according to the carrier modulation scheme of each layer included in the control information acquired by the TMCC decoding processing unit 613, Generate bit data. Further, the demapping processing unit 622 performs distance information (hereinafter referred to as “reception symbol point distance information”) between the “received OFDM symbol point” and the mapping point (transmission signal point) closest to the “received OFDM symbol point”. And reliability information is generated based on information on the magnitude of the channel characteristics of the carrier including the “received OFDM symbol point” obtained from the deinterleave processing unit 621 separately.

At this time, the demapping processing unit 622 accumulates the “distance information of received symbol points” for each OFDM symbol for a certain period, separately calculates the noise amount for each carrier included in the carrier including the OFDM symbol, Reliability information may be generated from the amount of noise for each, the estimation result of transmission path characteristics, and “distance information of received symbol points”.

The process of calculating the reliability information and using it in the subsequent decoding processing unit 632 as described above is called “soft decision”.

Then, the demapping processing unit 622 outputs the bit data generated from the mapping point closest to the “received OFDM symbol point” and the reliability information to the bit deinterleaving processing unit 631.

The bit deinterleave processing unit 631 rearranges the bit data and reliability information obtained from the demapping processing unit 622 into the original order in accordance with the ISDB-T standard, and the rearranged bit data and reliability information. Is output to the decoding processing unit 632.

The decryption processing unit 632 obtains bit data and reliability information from the bit deinterleave processing unit 631. The decoding processing unit 632 obtains the bit data obtained from the bit deinterleaving processing unit 631 according to the coding rate of the inner code of each layer (coding rate of the convolutional code) included in the control information acquired by the TMCC decoding processing unit 613. A dummy bit is inserted in the bit position thinned out on the transmission side with respect to the data string, and the value is undefined. The decoding processing unit 632 performs decoding processing on the received bit data by weighting the input data according to the reliability information. Currently, a decoding process called Viterbi decoding is widely used, but a process according to another decoding algorithm may be used. The decryption processing unit 632 outputs a data string as a decryption result to the byte deinterleave processing unit 633.

The byte deinterleave processing unit 633 receives the data sequence of the decoding result from the decoding processing unit 632, rearranges the received data sequence of the decoding result into the original order according to the ISDB-T standard, and the energy despreading processing unit 634. Outputs the data sequence rearranged to.

The energy despreading processing unit 634 performs processing for restoring the energy spreading processing performed on the transmission side according to the ISDB-T standard for the data sequence obtained from the byte deinterleaving processing unit 633, and after conversion. The data string is output to the RS decoding processing unit 635.

The RS decoding processing unit 635 receives the data sequence from the energy spreading processing unit 634, performs a Reed-Solomon decoding process on the received data sequence using the assigned outer code, and sends the Reed-Solomon to the TS reproduction processing unit 671. Output the decrypted data string.

The TS reproduction processing unit 671 obtains the data string after Reed-Solomon decoding from the RS decoding processing unit 635. The data string after Reed-Solomon decoding obtained from the RS decoding processing unit 635 is a packet of a transport stream. Since the number of packets of the transport stream obtained from the RS decoding processing unit 635 differs depending on the transmission parameter, the TS reproduction processing unit 671 supplements an appropriate number of null packets, and does not depend on the transmission parameter, Adjust so that the number of packets is output. The TS reproduction processing unit 671 outputs the transport stream packet after complementing the null packet to the TS decoding processing unit 672.

The TS decode processing unit 672 obtains the transport stream packet output from the TS playback processing unit 671, and based on the information included in the transport stream, a video packet, an audio packet, and a PCR (Program Clock Reference) packet Are output to the MPEG decoding processing unit 673.

The MPEG decode processing unit 673 includes a video decoder and an audio decoder. The video decoder extracts video packets from the transport stream packets obtained from the TS decoding processing unit 672, decodes the data, and generates image data. The audio decoder extracts an audio packet from the transport stream obtained from the TS decode processing unit 672, decodes the data, and generates audio data.

Then, the MPEG decoding processing unit 673 adjusts the output timing of the image data and the audio data based on the time information included in the PCR packet, and then outputs the image data and the audio data to a display device or the like.

As described above, according to the configuration shown in FIG. 14, after receiving the ISDB-T broadcast wave, various processes are performed, so that viewing and recording of images and sounds can be performed.

However, in digital broadcasting, when the received signal level falls below a certain level, or when the amount of radio interference exceeds a certain level, the reception state deteriorates rapidly, and images and sounds are partially lost, and video and Audio interruption occurs. The factors that cause deterioration in the reception quality of terrestrial digital broadcasting include delayed waves that are reflected from the signal itself to buildings and mountains, analog TV broadcast waves that are received in the same frequency band, and signals that are at a high level outside the band. Intermodulation distortion caused by distortion due to noise, noise signals such as unwanted radiation generated in the receiver or other devices, etc. can be considered, and if the interference signal level is higher than a certain level with respect to the signal to be received, the reception quality The impact on will appear.

In this specification, analog TV broadcast waves superimposed on frequency bands used in digital broadcasting, intermodulation distortion, noise signals due to unnecessary radiation such as harmonics of clock signals, etc. An interference signal having a biased characteristic is called a frequency selective interference signal, and a technique for improving resistance to the frequency selective interference signal will be described.

Various techniques for detecting and removing the influence of a frequency selective interference signal superimposed on a signal when receiving and demodulating a signal subjected to multicarrier modulation such as OFDM modulation have been disclosed.

For example, in Patent Document 1, in the process of demodulating an OFDM signal, the distance between the demodulation signal point of each of a plurality of carriers and the representative reception symbol point is measured for each carrier and integrated in the time direction to determine the magnitude of the dispersion of the demodulation signal. The C / N for each carrier is detected by comparing the magnitude of dispersion for each carrier, and the carrier having a poor C / N is considered to be disturbed by frequency selectivity. There is disclosed an OFDM receiving apparatus that performs stepwise weighting on a demodulated signal based on information and performs error correction processing by a method called soft decision. The value of the distance between the demodulated signal point and the representative reception symbol point is also called MER (Modulation Error Ratio), and uses the MER value calculated for each carrier in the soft decision processing.

Further, in Patent Document 2, when a transmission path characteristic between transmission and reception is estimated and compensated using a pilot signal regularly arranged in an OFDM signal, a frequency selective interference signal is detected. Is detected, the pilot signal that exists in the vicinity of the disturbed carrier is not used for estimating the channel characteristics, and the pilot signal that has detected the disturbing signal from the pilot signal that is not affected by the disturbing signal is not used. An OFDM receiver used for signal processing by estimating peripheral transmission path characteristics is disclosed.

Japanese Patent No. 2945570 Japanese Patent No. 3363806

In Patent Document 1, a frequency-selective interference signal is detected from an integral value of distances between demodulated signal points and representative reception symbol points of a plurality of carriers. Specifically, a hard decision process is performed in which the equalized symbol is regarded as being received at the closest representative symbol point, and the distance between the equalized symbol point and the closest representative symbol point in the time direction for each carrier. Is used as an indicator of the amount of interference signal. However, when the carrier is subjected to multi-level QAM modulation such as 64QAM, the interference signal amount is larger than the inter-code distance of the 64QAM signal, or the interference signal overlaps with the pilot carrier, resulting in a large estimation error of the transmission path characteristics. As a result of dividing the received signal by the transmission path characteristic including the estimation error, the equalized symbol point may be far away from the transmission symbol point. At this time, if the distance between the symbol point after equalization and the closest symbol point is calculated, the original transmission signal point exists further away, and there is a problem that the amount of interference signal is estimated to be small.

Further, the error correction capability is improved by using the calculated interference signal amount as reliability information in the error correction code processing unit, but as described above, the distance between the symbol point after equalization and the closest symbol point If the integrated value of is an interference signal amount, there is a possibility that the detected value of the interference signal amount includes an error, so that the error correction effect in the error correction processing unit cannot be maximized.

In Patent Document 2, a frequency-selective interference signal is detected. If a frequency-selective interference signal is detected, a pilot signal existing around the interfered carrier is not used for estimation of transmission path characteristics. I have to. However, when the carrier that transmits the actual data is affected by the frequency selective interference signal, the signal processing is performed in a state where the influence of the frequency selective interference signal of the carrier that transmits the actual data remains as it is. Therefore, a sufficient error correction effect cannot be expected.

An object of the present invention is to solve the above-described conventional problems, and to provide a multicarrier modulation signal receiving apparatus and an integrated circuit capable of maximizing the effect of error correction.

In order to achieve the above object, a multicarrier modulation signal receiver of the present invention demodulates a multicarrier modulation signal and generates a data sequence of reception symbol points and transmission path characteristic estimation results for each carrier; A deinterleave processing unit for rearranging a data sequence of estimation results of reception symbol points and transmission path characteristics input from the demodulation unit, and a rearranged reception symbol point and transmission path characteristics input from the deinterleaving processing unit A first demapping processing unit that generates bit data and reliability information of the bit data from the estimation result data sequence, and based on the reliability information of the bit data input from the first demapping processing unit A first error correction unit that performs error correction processing and generates data obtained by restoring a transmission signal sequence; and a transmission signal that is input from the first error correction unit An encoding unit that performs an encoding process on the data whose columns have been restored, and generates a signal indicating an error-correctable range for determining whether the data after the encoding process is generated from data that could not be error-corrected; , By dividing the data subjected to the encoding process input from the encoding unit in accordance with a carrier modulation scheme and performing mapping to generate mapping point information, and one or a plurality of calculation source information of the mapping point information A mapping processor that generates error presence / absence information of mapping points from a signal indicating an error-correctable range corresponding to each of the data, rearranged received symbol points input from the deinterleaver, and the mapping process The received symbol based on mapping point information and mapping point error presence / absence information input from the unit An inter-code distance calculation / accumulation processing unit that calculates a distance between the mapping point information and the mapping point information, a rearranged received symbol point input from the deinterleave processing unit, and a data string of estimation results of transmission path characteristics, the mapping Bits from mapping point information inputted from the processing unit, mapping point error presence / absence information, and distance information between the received symbol point and the mapping point information inputted from the inter-code distance calculation / accumulation processing unit A second demapping processing unit for generating data and reliability information of the bit data, and performing error correction processing based on the bit data and the reliability information input from the second demapping processing unit, And a second error correction unit for generating the signal sequence.

The integrated circuit of the present invention also includes a demodulation circuit that demodulates a multi-carrier modulation signal and generates a data sequence of estimation results of reception symbol points and transmission path characteristics for each carrier, and reception symbol points input from the demodulation circuit And a deinterleaving processing circuit for rearranging the data sequence of the estimation result of the transmission path characteristics, bit data from the data string of the rearranged received symbol points and the estimation result of the transmission path characteristics inputted from the deinterleaving processing circuit, and A first demapping processing circuit for generating reliability information of the bit data, and error correction processing based on the reliability information of the bit data input from the first demapping processing circuit, A first error correction circuit that generates restored data, and data obtained by restoring a transmission signal sequence input from the first error correction circuit An encoding circuit that performs encoding processing and generates a signal indicating an error-correctable range for determining whether or not the data after encoding processing was generated from data that could not be error-corrected, and input from the encoding circuit The encoded data is divided according to the carrier modulation method and mapped to generate mapping point information, and corresponds to each of one or a plurality of data from which the mapping point information is calculated Mapping processing circuit for generating error presence / absence information of mapping points from a signal indicating an error correctable range, rearranged received symbol points input from the deinterleave processing circuit, and mapping points input from the mapping processing circuit The received symbol point and the mapping An inter-code distance calculation / accumulation processing circuit for calculating a distance to point information, a rearranged received symbol point input from the deinterleave processing circuit, and a data string of estimation results of transmission path characteristics, from the mapping processing circuit From the input mapping point information and mapping point error presence / absence information, and the distance information between the received symbol point and the mapping point information input from the inter-code distance calculation / accumulation processing circuit, bit data and A second demapping processing circuit for generating bit data reliability information; and an original signal sequence that performs error correction processing based on the bit data and the reliability information input from the second demapping processing circuit. And a second error correction circuit for generating.

According to each of the multicarrier modulation signal receiving apparatus and the integrated circuit, the effect of error correction can be maximized.

In the multicarrier modulation signal receiving apparatus, the first demapping processing unit further generates the reliability information, and further receives the received symbol point input from the inter-code distance calculation / accumulation processing unit. You may make it perform using distance information with the information of the said mapping point.

In the above integrated circuit, the first demapping processing circuit further generates the reliability information, and further adds the received symbol points and the mapping points input from the inter-code distance calculation / accumulation processing circuit. You may make it perform using distance information with information.

According to each of the multicarrier modulation signal receiving apparatus and the integrated circuit, in addition to the second demapping processing unit, the first demapping processing unit also uses the calculation result of the inter-code distance calculation / accumulation processing unit. The reception performance can be further improved.

In the multicarrier modulation signal receiving apparatus, the second demapping processing unit is input from the deinterleaving processing unit based on error presence / absence information of mapping point information input from the mapping processing unit. The reliability information may be generated by generating a new signal point from the rearranged received symbol points and the mapping point information input from the mapping processing unit.

According to this, the accuracy of the reliability information of the second demapping processing unit can be improved.

In the multicarrier modulation signal receiving apparatus, the inter-code distance calculation / accumulation processing unit may perform mapping input from the mapping processing unit based on mapping point error presence / absence information input from the mapping processing unit. When it is determined that the point information is generated only from the data that has been error-corrected, the rearranged received symbol points input from the deinterleave processing unit and the mapping point information input from the mapping processing unit When the mapping point information input from the mapping processor is determined to have been generated only from data that could not be error-corrected, it is input from the deinterleave processor. The rearranged received symbol point and the transmission signal point closest to the received symbol point When the Euclidean distance is integrated for each carrier, and it is determined that the mapping point information input from the mapping processing unit is generated from data that could be corrected and data that could not be corrected, the error could be corrected. Among the code points determined from the data, the code point closest to the rearranged received symbol point input from the deinterleave processing unit is regarded as a transmission signal point, and the rearranged input input from the deinterleave processing unit The Euclidean distance between the reception symbol point and the code point regarded as the transmission signal point may be integrated for each carrier, and the integration result may be output as the distance between the reception symbol point and the mapping point information.

According to this, the accuracy of the calculation result of the inter-code distance calculation / accumulation processing unit can be improved.

In the multicarrier modulation signal receiving apparatus, the inter-symbol distance calculation / accumulation processing unit is configured to calculate the mapping point information input from the mapping processing unit from data that has been error-corrected and data that has not been error-corrected. When it is determined that the generated Euclidean distance between the rearranged received symbol point input from the deinterleave processing unit and the code point regarded as the transmission signal point is reduced, The Euclidean distance may be integrated in units of carriers.

According to this, the accuracy of the calculation result of the inter-code distance calculation / accumulation processing unit can be further improved.

In the multicarrier modulation signal receiving apparatus, the second error correction unit counts the number of error correction processes performed by the second error correction unit and the number of error correction processes is less than a predetermined number. May be further provided with an error correction count unit that outputs the output of the above to the encoding unit.

According to this, when the number of error correction processes is set to 2 or more, for example, the error correction process in the second error correction unit is repeated, so that the reception performance can be further improved.

The multi-carrier modulation signal receiving apparatus of the present invention demodulates a multi-carrier modulation signal, generates a data sequence of reception symbol points and transmission path characteristic estimation results for each carrier, and a reception input from the demodulation unit A deinterleave processing unit that rearranges the data sequence of the symbol point and the channel characteristic estimation result, and a bit from the rearranged received symbol point and the channel sequence estimation result data sequence that are input from the deinterleave processing unit. A first demapping unit that generates data and reliability information of the bit data, a first error correction unit that performs error correction processing and generates data obtained by restoring a transmission signal sequence, and the first error Data on which the transmission signal sequence generated by the correction unit is restored and the data after the encoding process cannot be error-corrected An encoder that generates a signal indicating an error-correctable range for determining whether or not the error correction has been generated, and the number of error correction processes performed by the first error correction unit. An error correction count unit that outputs the output of the first error correction unit to the encoding unit when the number of times is less than a predetermined number of times, and data that has been subjected to encoding processing input from the encoding unit is divided according to a carrier modulation scheme Then, mapping is performed to generate mapping point information, and mapping point error presence / absence information is obtained from a signal indicating an error correctable range corresponding to one or a plurality of data from which the mapping point information is calculated. A mapping processor to be generated, a rearranged received symbol point input from the deinterleave processor, and an input from the mapping processor The inter-code distance calculation / accumulation processing unit that calculates the distance between the received symbol point and the mapping point information based on the information on the ping point and the error presence / absence information on the mapping point, and the deinterleave processing unit. A data string of rearranged received symbol points and transmission path characteristic estimation results, mapping point information input from the mapping processing unit and mapping point error presence / absence information, and input from the inter-code distance calculation / accumulation processing unit A second demapping processing unit that generates bit data and reliability information of the bit data from distance information between the received symbol point and the mapping point information to be output to the first error correction unit And the first error correction unit performs error correction based on reliability information of bit data input from the first demapping processing unit. Processing is performed to generate data in which the transmission signal sequence is restored, and error correction processing is performed based on the bit data input from the second demapping processing unit 153 and the reliability information of the bit data.

According to the above multicarrier modulation signal receiver, the effect of error correction can be maximized. Further, since only one processing block for performing error correction processing is required, it is possible to avoid an increase in the scale of the apparatus. Furthermore, when the number of error correction processes is set to 3 or more, for example, the error correction process is repeated, so that the reception performance can be further improved.

According to the multicarrier modulation signal receiving apparatus, in addition to the second demapping processing unit, the first demapping processing unit also uses the calculation result of the inter-code distance calculation / accumulation processing unit. Improvement is achieved.

1 is a block diagram showing a configuration of a multicarrier modulation signal receiving apparatus in Embodiment 1 of the present invention. The block diagram which shows the detailed structure of the multicarrier modulation signal receiver of FIG. FIG. 3 is a configuration diagram of a convolutional code processing unit 145 in FIG. 2. FIG. 3 is a configuration diagram of an error information calculation processing unit 146 in FIG. 2. FIG. 3 is a supplementary explanatory diagram of processing of the mapping processing unit 151 of FIGS. 1 and 2. The figure which shows the relationship between noise amount and MER (Modulation Error Ratio: modulation error ratio). The figure for demonstrating the correction method of the Euclidean distance calculated in the intersymbol distance calculation and accumulation process part 152 of FIG.1 and FIG.2. The block diagram which shows the structure of the multicarrier modulation signal receiver in the modification of Embodiment 1 of this invention. The block diagram which shows the structure of the multicarrier modulation signal receiver in the other modification of Embodiment 1 of this invention. The block diagram which shows the structure of the multicarrier modulation signal receiver in Embodiment 2 of this invention. The block diagram which shows the detailed structure of the multicarrier modulation signal receiver of FIG. The block diagram which shows the structure of the multicarrier modulation signal receiver in the modification of Embodiment 2 of this invention. The block diagram which shows the structure of the multicarrier modulation signal receiver in the other modification of Embodiment 2 of this invention. The block diagram which shows the structure of the conventional multicarrier modulation signal receiver.

(Embodiment 1)
Embodiment 1 of the present invention will be described below with reference to the drawings.

The description of the first embodiment will be made according to the ISDB-T system, which is a Japanese terrestrial digital broadcasting standard. Although there is a difference from other systems such as the DVB-T system, which does not necessarily include processing called interleave processing or hierarchical transmission, it does not greatly affect the concept of the present invention. The description of is omitted. Further, since the ISDB-T system is a known standard, only a minimum description will be given here. The same applies to the second embodiment described later.

FIG. 1 is a block diagram showing a configuration of a multicarrier modulation signal receiving apparatus according to Embodiment 1, and FIG. 2 is a block diagram showing a detailed configuration of the multicarrier modulation signal receiving apparatus of FIG.

As shown in FIG. 1, the multicarrier modulation signal receiving apparatus according to the first embodiment includes an antenna unit 101, a tuner unit 102, an A / D conversion processing unit 103, a demodulation unit 110, and a deinterleave processing unit 121. The first demapping processing unit 122, the first error correction unit 130, the encoding unit 140, the mapping processing unit 151, the inter-code distance calculation / accumulation processing unit 152, and the second demapping processing. Section 153, second error correction section 160, TS reproduction processing section 171, TS decode processing section 172, and MPEG decode processing section 173.

As shown in FIG. 2, the demodulation unit 110 in FIG. 1 includes an orthogonal detection processing unit 111, an FFT processing unit 112, a TMCC decoding processing unit 113, and an equalization processing unit 114. Further, as shown in FIG. 2, the first error correction unit 130 of FIG. 1 includes a first bit deinterleaving processing unit 131, a first decoding processing unit 132, and a first byte deinterleaving processing unit 133. And a first energy despreading processing unit 134 and a first RS decoding processing unit 135. Further, as shown in FIG. 2, the encoding unit 140 in FIG. 1 includes an RS code processing unit 141, an error information addition processing unit 142, an energy spread processing unit 143, a byte interleave processing unit 144, and a convolutional code processing. 145, error information calculation processing unit 146, and bit interleaving processing unit 147. Further, as shown in FIG. 2, the second error correction unit 160 in FIG. 1 includes a second bit deinterleaving processing unit 161, a second decoding processing unit 162, and a second byte deinterleaving processing unit 163. And a second energy despreading processing unit 164 and a second RS decoding processing unit 165.

Next, the configuration of the multicarrier modulation signal receiving apparatus according to the first embodiment in FIGS. 1 and 2 is compared with the configuration of the conventional multicarrier modulation signal receiving apparatus in FIG.

Compared with the conventional multicarrier modulation signal receiving apparatus, the multicarrier modulation signal receiving apparatus in Embodiment 1 includes a configuration of antenna unit 101 to deinterleave processing unit 121, and antenna unit 601 to deinterleave processing unit 621. The configuration is the same, and the configuration of the TS playback processing unit 171 to the MPEG decoding processing unit 173 is the same as the configuration of the TS playback processing unit 671 to the MPEG decoding processing unit 673. The multicarrier modulation signal receiving apparatus according to the first embodiment has a configuration in which different processing blocks are added between the deinterleave processing unit 621 and the TS reproduction processing unit 671 of the conventional multicarrier modulation signal receiving apparatus. Specifically, the output signal of the first RS decoding processing unit 135 in FIG. 2 passes through the encoding unit 140 and the mapping processing unit 151 for performing the encoding process again, and then to the second demapping processing unit 153. The TS reproduction processing unit 171 outputs a transport stream signal after the second error correction unit 160 performs decoding processing again on the input signal output from the second demapping processing unit 153. Yes.

Hereinafter, the operation of each block in FIGS. 1 and 2 will be described in order.

The tuner unit 102 selects a signal in a predetermined frequency band from the signal received by the antenna unit 101 and outputs it to the A / D conversion processing unit 103. The A / D conversion processing unit 103 samples the OFDM signal output from the tuner unit 102, converts the signal into a digital signal, and outputs the digital signal to the demodulation unit 110.

The demodulation unit 110 demodulates the OFDM signal obtained from the A / D conversion processing unit 103, and generates carrier unit data. Hereinafter, the operation of the demodulation unit 110 will be described in detail with reference to FIG.

The quadrature detection processing unit 111 multiplies the OFDM signal obtained from the A / D conversion processing unit 103 by a sine wave signal having the same frequency as the reference carrier wave, converts the signal into a baseband OFDM signal, and outputs the signal to the FFT processing unit 112. To do.

The FFT processing unit 112 extracts a signal sequence of an effective symbol period from the baseband OFDM signal output from the quadrature detection processing unit 111. Then, the FFT processing unit 112 performs discrete Fourier transform on the extracted signal sequence, generates a complex signal, and transmits the complex signal obtained by the discrete Fourier transform to the TMCC decoding processing unit 113 and the equalization processing unit 114. Is output.

The TMCC decoding processing unit 113 obtains a complex signal from the FFT processing unit 112. The TMCC decoding processing unit 113 detects and extracts a TMCC signal from the OFDM symbol, performs demodulation processing corresponding to DBPSK in the time direction on the extracted TMCC signal, and transmits control information transmitted as a TMCC signal from the result of the demodulation processing The TMCC decoding processing unit 113 does not clearly indicate the output destination component in FIG. 2, but outputs the information included in the control information to the component that requires the information for processing. To do. The control signal transmitted by the TMCC signal includes, for example, the time interleave length, the carrier modulation scheme of each layer, and the coding rate of the inner code (convolutional code in the ISDB-T standard). Details of the TMCC signal are described in the prior art.

In the ISDB-T standard, a plurality of layers having different transmission characteristics can be transmitted simultaneously, and the maximum number of layers is three. When the number of layers is 2 or 3, the output of the deinterleave processing unit 121 is divided into layers, and the first energy despreading processing unit 134 from the first demapping processing unit 122 performs processing for each layer, Thereafter, the layers are combined and input to the first RS decoding processing unit 135. Further, the outputs of the RS code processing unit 141 and the error information addition processing unit 142 are divided into layers, and the energy diffusion unit 143 to the second energy diffusion processing unit 164 perform processing for each layer, and then the layers are combined and processed. 2 to the RS decoding processing unit 165.

The equalization processing unit 114 receives the complex signal from the FFT processing unit 112. The equalization processing unit 114 detects and extracts SP signals that are discretely arranged from the OFDM symbol. The equalization processing unit 114 divides the extracted SP signal by a known complex signal value to estimate the transmission path characteristic (transmission path characteristic of the carrier on which the SP signal is arranged) between transmission and reception of the SP signal position. The equalization processing unit 114 performs interpolation processing based on the estimated values of the transmission path characteristics of the SP signal positions discretely arranged in the OFDM signal, so that the transmission path characteristics of each carrier between the SP signals. Is estimated. Then, the equalization processing unit 114 divides each OFDM symbol by the estimated transmission path characteristic of each carrier to obtain information on the OFDM symbol point that compensates for the influence of the transmission path. The equalization processing unit 114 includes information on OFDM symbol points (“received OFDM symbol points”) in which the influence of the transmission channel is compensated, and complex signal that is an estimation result of transmission channel characteristics corresponding to each of the “received OFDM symbol points”. Is output to the deinterleave processing unit 121.

The deinterleave processing unit 121 sequentially receives the “received OFDM symbol point” and the data string of the estimation result of the channel characteristics from the equalization processing unit 114. Then, the deinterleave processing unit 121 rearranges the received “received OFDM symbol point” and the data string of the transmission path characteristic estimation result. The rearrangement rules are defined in the ISDB-T standard, and the deinterleave processing unit 121 performs processing for returning the signals rearranged randomly in the time direction and the frequency direction to the original order in the interleaving process on the transmission side. Do. Then, the deinterleaving unit 121 outputs the “received OFDM symbol points” rearranged to the first demapping processing unit 122 and the data string of the estimation result of the transmission path characteristics. In addition, the deinterleaving unit 121 rearranges the data string of “received OFDM symbol points” rearranged in the inter-code distance calculation / accumulation processing unit 152 with respect to the second demapping processing unit 153 and receives “received”. The data string of the “OFDM symbol point” and the estimation result of the transmission path characteristics is output. However, the rearrangement in the time direction is performed according to the time interleave length of each segment included in the control information acquired by the TMCC decoding processing unit 113.

The first demapping processing unit 122 obtains the “received OFDM symbol points” rearranged from the deinterleaving processing unit 121 and the data string of the estimation result of the transmission path characteristics. The first demapping processing unit 122 regards the mapping point closest to the “received OFDM symbol point” as the transmission signal point according to the carrier modulation scheme of each layer included in the control information acquired by the TMCC decoding processing unit 113. , Generate bit data. In addition, the first demapping processing unit 122 performs distance information between the “received OFDM symbol point” and the mapping point (transmission signal point) closest to the “received OFDM symbol point” (“distance information of the received symbol point”). And reliability information is generated based on the information of the data string of the estimation result of the transmission path characteristics separately obtained from the deinterleave processing unit 121.

At this time, the first demapping processing unit 122 accumulates the “distance information of received symbol points” for each OFDM symbol for a certain period, and separately calculates the amount of noise for each carrier included in the carrier including the OFDM symbol. In addition, the reliability information may be generated from the noise amount for each carrier, the estimation result of the transmission path characteristics, and the “distance information of received symbol points”.

In addition, since the generation of reliability information in the first demapping processing unit 122 of Embodiment 1 can use the same known method as the generation of reliability information in the demapping processing unit 622 of the conventional example, Detailed description is omitted.

Then, the first demapping processing unit 122 outputs the generated bit data and reliability information to the first error correction unit 130.

The first error correction unit 130 performs error correction processing based on the bit data obtained from the first demapping processing unit 122 and the reliability information, and generates an original signal sequence. Hereinafter, the operation of the first error correction unit 130 will be described in detail with reference to FIG.

The first bit deinterleave processing unit 131 rearranges the bit data and reliability information obtained from the first demapping processing unit 122 into the original order according to the ISDB-T standard, and rearranges the bit data. And the reliability information are output to the first decoding processing unit 132.

The first decoding processing unit 132 obtains bit data and reliability information from the first bit deinterleaving processing unit 131. The first decoding processing unit 132 is a first bit deinterleaving processing unit according to the coding rate of the inner code of each layer (coding rate of the convolutional code) included in the control information acquired by the TMCC decoding processing unit 113 A dummy bit is inserted into the bit position thinned out on the transmission side with respect to the data string of bit data obtained from 131, and the value is undefined. The first decoding processing unit 132 performs decoding processing by weighting the received bit data according to the reliability information. Currently, a decoding process called Viterbi decoding is widely used, but a process according to another decoding algorithm may be used. The first decoding processing unit 132 outputs a data string as a decoding result to the first byte deinterleaving processing unit 133.

The first byte deinterleave processing unit 133 receives the data sequence of the decoding result from the first decoding processing unit 132, rearranges the received data sequence of the decoding result to the original order in accordance with the ISDB-T standard, The rearranged data string is output to the first energy despreading processing unit 134.

The first energy despreading processing unit 134 performs processing for returning the energy spreading processing performed on the transmission side to the data sequence obtained from the first byte deinterleaving processing unit 133 according to the ISDB-T standard. The converted data string is output to the first RS decoding processing unit 135.

Processing blocks from the first RS decoding processing unit 135 to the second RS decoding processing unit 165 described below are processing blocks newly added to FIG. 14 or processing blocks having different connection destinations of output signals.

The first RS decoding processing unit 135 receives the data sequence from the first energy diffusion processing unit 134, performs Reed-Solomon decoding processing on the received data sequence using the assigned outer code, and performs Reed-Solomon decoding The data stream of the transport stream packet thus processed is output to the RS code processing unit 141 in the encoding unit 140. At the same time, the first RS decoding processing unit 135 transmits to the error information addition processing unit 142 in the encoding unit 140 information indicating whether error correction has been performed in units of transport stream packets, A signal for determining the first byte of the port stream packet is output. Note that an error flag attached to a transport stream packet can be used as information on whether or not an error has been corrected in units of transport stream packets. Further, the transport stream includes a synchronization byte, and the synchronization byte can be used as a signal for determining the first byte of the transport stream packet. For this reason, it is assumed that first RS decoding processing section 135 outputs a data stream of the transport stream to error information addition processing section 142 in encoding section 140.

The encoding unit 140 performs the same encoding process as the encoding process performed in the transmission apparatus on the data stream of the transport stream packet obtained from the first RS decoding processing unit 135. Then, in parallel with the encoding process, the encoding unit 140 generates a signal for determining whether the encoded signal is generated from a signal including an error. Hereinafter, the operation of the encoding unit 140 will be described in detail with reference to FIG.

The RS code processing unit 141 performs Reed-Solomon code processing on the transport stream packet data obtained from the first RS decoding processing unit 135 for each transport stream. In the Japanese terrestrial digital broadcasting system, a process called a shortened Reed-Solomon code (204, 188) is performed, and an outer code for enabling correction of random errors from 204 bytes to 8 bytes is given. The RS code processing unit 141 outputs data obtained by adding an outer code to the transport stream data to the energy spreading processing unit 143.

The error information addition processing unit 142 obtains the data stream of the transport stream packet subjected to Reed-Solomon decoding from the first RS decoding processing unit 135. Then, the error information addition processing unit 142 is based on the information on the result of whether or not the error correction of the packet given to each packet in the transport stream data is possible (error flag given to the transport stream packet). In addition, information indicating whether or not error correction is possible (information indicating whether or not error correction has been performed) is generated for each packet, and a signal for determining the synchronization byte part at the head of the packet from the synchronization byte included in the transport stream is generated. . Then, the error information addition processing unit 142 outputs to the byte interleaving processing unit 144 a signal for determining whether or not error correction is possible and a synchronous byte portion at the beginning of the packet.

Alternatively, the error information addition processing unit 142 obtains the data stream of the transport stream that is output from the first RS decoding processing unit 135 to the RS code processing unit 141, and the RS code processing unit 141 and an energy spreading process to be described later If the processing delay time in the unit 143 is known, only information on whether or not error correction is possible in units of packets is generated, and the output timing of a signal indicating whether or not error correction is possible is output from the energy diffusion processing unit 143 described later. It is good also as a structure aligned with a data sequence. At this time, it is necessary to generate a signal indicating whether or not error correction is possible in consideration of the parity part signal added by the RS code processing unit 141.

The energy spread processing unit 143 obtains a data string obtained by adding an outer code to the data of the transport stream from the RS code processing unit 141. Then, the energy spread processing unit 143 performs energy spread processing on the transport stream signal excluding the synchronization bytes using a pseudo-random code sequence defined by the ISDB-T standard, and sends data to the byte interleave processing unit 144. Output a column.

The byte interleave processing unit 144 receives the data string from the energy diffusion processing unit 143, “error correction availability information” from the error information addition processing unit 142 (the data obtained from the energy diffusion processing unit 143 is the first RS decoding processing unit In 135, information indicating whether or not error correction has been performed is obtained. At this time, it is assumed that the “error correction propriety information” is aligned with the data sequence obtained from the energy diffusion processing unit 143.

The byte interleave processing unit 144 then converts the data sequence obtained from the energy diffusion processing unit 143 and the “error correction availability information” obtained from the error information addition processing unit 142 into byte units in the order defined by the ISDB-T standard. Then, the rearranged data string is output to the convolutional code processing unit 145, and the rearranged “error correction availability information” is output to the error information calculation processing unit 146. By the way, in the ISDB-T standard, when the carrier modulation method differs depending on the layer, it is necessary to match the delay time for each layer. Therefore, in the configuration of FIG. 2, the byte interleave processing unit 144 performs the delay correction processing at the same time. Shall be done.

The convolutional code processing unit 145 performs convolutional code processing on the data sequence obtained from the byte interleaving processing unit 144, and encodes the inner-code coding rate of each layer included in the control information acquired by the TMCC decoding processing unit 113 ( After the data is thinned according to the convolutional code rate, the data string is output to the bit interleave processing unit 147.

The error information calculation processing unit 146 obtains, from the byte interleaving processing unit 144, “error correction enable / disable information” data that has undergone byte interleaving rearrangement processing. The data processing unit of the error information calculation processing unit 146 is a bit unit. Then, the error information calculation processing unit 146 generates data indicating a range in which data including an error affects the calculation in the convolutional code processing unit 145. Then, the error information calculation processing unit 146 provides the bit interleaving processing unit 147 with data indicating whether or not the data output from the convolutional code processing unit 145 may have an error (hereinafter, “error correction is possible”). This is called a “signal indicating the range.”).

Here, the processing procedure of the convolutional code processing unit 145 and the error information calculation processing unit 146 will be described with reference to FIGS. 3 and 4.

FIG. 3 is a configuration example of an encoding circuit for generating a convolutional code in the convolutional code processing unit 145. One code generator polynomial G1 = (1,1,1,1,0,0,1), the other code generator polynomial G2 = (1,0,1,1,0,1,1), An encoding circuit with a constraint length k = 7 and an encoding rate of 1/2 is shown. Data input from the input side is input to the delay circuit, the output of each delay element (“D” in FIG. 3) is subjected to an exclusive OR operation according to a generator polynomial, and two data of X output and Y output are obtained. Is output.

On the other hand, FIG. 4 shows an arithmetic processing circuit performed by the error information arithmetic processing unit 146. The arithmetic processing circuit of FIG. 4 is different from the encoding circuit of FIG. 4 in that the exclusive OR calculator for generating the X output and the Y output is a logical OR calculator. If the “error correction enable / disable information” obtained from the byte interleave processing unit 144 by the error information calculation processing unit 146 in FIG. 4 is data that can be corrected by the first RS decoding processing unit 135, the error correction is performed. If the data could not be obtained, it is assumed to be “1”. The error information arithmetic processing unit 146 is data indicating whether or not the data output from the convolutional code processing unit 145 is generated from data that may have an error (“signal indicating error-correctable range”). ) Is “1” if the data output from the convolutional code processing unit 145 is generated from data that may have an error, and is generated from data that may have an error. Otherwise, “0” is output.

However, the convolutional code processing unit 145 and the error information calculation processing unit 146 are configured according to the encoding rate of the inner code of each layer (coding rate of the convolutional code) acquired by the TMCC decoding processing unit 113. Select and output X output and Y output (thinning out the X output and Y output of the encoder). For this reason, the selection procedure of the X output and the Y output in the convolutional code processing unit 145 and the error information calculation processing unit 146 is the same procedure.

The bit interleave processing unit 147 obtains the data string subjected to the convolutional code processing from the convolutional code processing unit 145 and obtains a “signal indicating an error-correctable range” from the error information calculation processing unit 146. The bit interleave processing unit 147 takes into consideration that the data sequence obtained from the convolutional code processing unit 145 and the “signal indicating the error-correctable range” obtained from the error information calculation processing unit 146 do not shift in the time direction. Then, the rearrangement processing of the bits of the two data strings is performed according to the ISDB-T standard, and the information of the rearranged data strings and the “signal indicating the error-correctable range” is output to the mapping processing unit 151.

The mapping processing unit 151 obtains a data string after bit interleaving and a “signal indicating an error-correctable range” after bit interleaving from the bit interleaving processing unit 147. Then, the mapping processing unit 151 performs mapping by dividing the data sequence after bit interleaving into carrier units according to the carrier modulation scheme of each layer included in the control information acquired by the TMCC decoding processing unit 113. Using the case where the carrier modulation scheme is 16QAM as an example, the processing of the mapping processing unit 151 will be described with reference to FIG.

FIG. 5 shows the relationship between the input data pattern to the mapping processing unit 151 and mapping points when the carrier modulation scheme is 16QAM, and how the real number I and the imaginary number Q are assigned to 4-bit data. It is illustrated. In FIG. 5, complex signal points are assigned so that the inter-code distance between adjacent codes is 2. For example, the input data is (b0, b1, b2, b3) = (0, 0, 0, 0). If so, a complex signal of (I, Q) = (+ 3, +3) is assigned as a mapping point. The mapping processing unit 151 converts the data sequence after bit interleaving obtained from the bit interleaving processing unit 147 into a complex signal (hereinafter referred to as “mapping point information”) representing a mapping point determined from the carrier modulation scheme. At the same time, information including a “signal indicating an error-correctable range” after bit interleaving corresponding to each of one or a plurality of pieces of data of the mapping point calculation source (hereinafter referred to as “mapping point error presence / absence information”). Is output to the inter-code distance calculation / accumulation processing unit 152 and the second demapping processing unit 153.

The intersymbol distance calculation / accumulation processing unit 152 obtains from the mapping processing unit 151 a data string of “mapping point information” and “mapping point error presence / absence information” mapped according to the carrier modulation scheme. Further, the inter-code distance calculation / accumulation processing unit 152 obtains an OFDM symbol data sequence (hereinafter referred to as “information of received OFDM symbol points”) from the deinterleaving processing unit 121.

First, the inter-code distance calculation / accumulation processing unit 152 aligns the timings of “received OFDM symbol point information”, “mapping point information”, and “mapping point error presence / absence information”. Since the processing delay amount from the first demapping processing unit 122 to the mapping processing unit 151 or the data is processed in units of OFDM symbols, for example, the beginning of the OFDM symbol is determined, and “mapping point information” and “ The acquisition timing difference from “received OFDM symbol point information” may be counted and adjusted, or a signal indicating the OFDM symbol head may be generated and transmitted in each processing block.

Next, the inter-code distance calculation / accumulation processing unit 152 calculates a distance between “received OFDM symbol point information” and “mapping point information”. The distance is calculated according to the Euclidean distance calculation procedure. However, “mapping point error presence / absence information” needs to be considered when calculating the distance.

The inter-code distance calculation / accumulation processing unit 152 determines the content of the “mapping point error presence / absence information” corresponding to the “mapping point information”, and performs the following processing according to the content.

If the “mapping point error presence / absence information” corresponding to the “mapping point information” is error-free (if all of the data used to generate the “mapping point information” is error-corrected data) The inter-code distance calculation / accumulation processing unit 152 calculates the Euclidean distance between the complex signal of “mapping point information” and the complex signal of “received OFDM symbol point information”.

If the error is biased to one of the real part or imaginary part of the data used to generate the "mapping point information" in the "mapping point error presence / absence information", the inter-code distance is calculated. The accumulation processing unit 152 calculates the Euclidean distance between the complex signal of “information of received OFDM symbol points” and the complex signal of “information of mapping points” replaced by the following procedure.

For example, when only the imaginary part of “mapping point information” may have an error, the inter-code distance calculation / accumulation processing unit 152 replaces the imaginary part of “mapping point information” with “received OFDM”. Replace the imaginary part of the symbol point information with the imaginary part of the nearest symbol point. The real part of “mapping point information” is not replaced. Then, the inter-code distance calculation / accumulation processing unit 152 calculates the Euclidean distance between the “mapping point information” complex signal in which the imaginary part is replaced and the “received OFDM symbol point information” complex signal.

When there is a possibility that only the real part of “mapping point information” may have an error, the inter-code distance calculation / accumulation processing unit 152 replaces the real part of “mapping point information” with “received OFDM symbol points”. Is replaced with the real part of the nearest symbol point. The imaginary part of the “mapping point information” is not replaced. Then, the inter-code distance calculation / accumulation processing unit 152 calculates the Euclidean distance between the “mapping point information” complex signal and the “received OFDM symbol point information” complex signal with the real part replaced.

When there is a possibility that both the real part and the imaginary part of the data used for generating the “mapping point information” may contain an error, the inter-code distance calculation / accumulation processing unit 152 determines the real number of the “mapping point information”. The imaginary part and the imaginary part are replaced with a complex signal at a symbol point closest to “information on received OFDM symbol points”. Then, the inter-code distance calculation / accumulation processing unit 152 calculates the Euclidean distance between the complex signal of “mapping point information” in which the real part and the imaginary part are replaced and the complex signal of “information of the received OFDM symbol point”. . The MER (Modulation Error Ratio): Modulation error ratio is calculated by accumulating the Euclidean distance values calculated when there is a possibility that both the real part and the imaginary part of the data used for generating the “mapping point information” contain errors. ) And generally called value.

Thus, when there is a possibility that one of the real part or the imaginary part of the data used for generating the “mapping point information” or both the real part and the imaginary part may contain an error, the inter-code distance calculation / The accumulation processing unit 152 performs processing for replacing one of the real part or the imaginary part, or both of the real part and the imaginary part, and then receives the “symbol point closest to“ information of received OFDM symbol point ”and“ reception ”. The Euclidean distance with the “information on the OFDM symbol points” is calculated.

In the first embodiment, the inter-code distance calculation / accumulation processing unit 152 corrects the calculated Euclidean distance value. The correction procedure will be described with reference to FIGS.

FIG. 6 illustrates the relationship between the MER value obtained by integrating the Euclidean distance between the “symbol point closest to the“ received OFDM symbol point ”and the“ received OFDM symbol point ”and the amount of noise added to the signal. Is. The horizontal axis represents the amount of noise, and the vertical axis represents the magnitude of the MER value. The solid line in FIG. 6 indicates the MER value, and the dotted line indicates the amount of noise added to the signal. As shown in FIG. 6, when the amount of noise is smaller than the value “A”, the MER value and the amount of noise substantially match. On the other hand, when the noise amount becomes larger than the value “A”, a difference occurs between the MER value and the noise amount, and the MER value becomes smaller than the noise amount. This is because the added noise amount is larger than the inter-code distance of the QAM signal, while the Euclidean distance is calculated from the distance to the nearest code point, and as a result, the MER value is calculated to be small.

7 shows the error rate of the output signal (transport stream packet) of the first RS decoding processing unit 135 of FIG. 2 with respect to the noise amount, and the Euclidean distance calculated by the inter-code distance calculation / accumulation processing unit 152 for the noise amount. The cumulative value of is simultaneously shown. The relationship between the MER value and the accumulated value of the Euclidean distance calculated by the inter-code distance calculation / accumulation processing unit 152 with respect to the amount of noise added to the signal is shown.

Originally, in the demapping processing units such as the first demapping processing unit 122 and the second demapping processing unit 153, it is desirable to accurately obtain the amount of noise added to the signal.

MER (Modulation Error Ratio) is one of the commonly used techniques for calculating the amount of noise added to this signal. The MER is calculated from a value obtained by averaging the distance between the transmission signal point closest to the reception signal point and the reception signal point for a certain period. When the amount of noise added to the signal is small and the reception signal point is not far from the transmission signal point, the noise amount can be estimated with high accuracy. However, for example, in a multi-level modulation scheme such as 16QAM, when the amount of added noise is larger than the intersymbol distance, the nearest signal point from which the MER is calculated is not the correct transmission signal point, which is incorrect. The MER value is calculated based on the distance between the transmitted signal point and the received signal point, and a value smaller than the actually added noise amount is calculated. In FIG. 7, the noise amount for which a value smaller than the noise amount actually added by the MER value is “A”.

On the other hand, the cumulative value of the Euclidean distance value calculated by the inter-code distance calculation / accumulation processing unit 152 in the first embodiment is the first value even if the amount of noise added to the signal is larger than “A”. Since the error-corrected information is used in the RS decoding processing unit 135, an accurate noise amount can be estimated. Here, the amount of noise that is added to the signal and the output signal of the first RS decoding processing unit 135 starts to contain an error is defined as “B”. Then, since the distance between the correct transmission signal point and the reception signal point can be calculated while the noise amount is between “A” and “B”, the inter-code distance calculation / accumulation processing unit 152 estimates an accurate noise amount. be able to.

Next, when the amount of noise added to the signal increases from “B”, the first RS decoding processing unit 135 cannot perform error correction, and the output signal includes an error. Further, a noise amount at which all the output signals of the first RS decoding processing unit 135 start to contain errors is defined as “C”. When the noise amount ranges from “B” to “C”, the MER value and the distance between “received OFDM symbol point information” and “mapping point information” according to the error rate of the first RS decoding processing unit 135. A value obtained by combining the accumulated values of the Euclidean distance values calculated from the above is output.

As the amount of noise increases, the data error-corrected by the first RS decoding processing unit 135 decreases, and when the amount of noise becomes “C”, error correction of all data becomes impossible. When the noise amount is “C”, the noise amount calculated by the intersymbol distance calculation / accumulation processing unit 152 is the same value as the value calculated by the MER.

If the amount of noise further increases from “C”, there is no data that can be corrected by the first RS decoding processing unit 135, and accurate transmission signal point information cannot be obtained. The amount of noise calculated at 152 is the same value as the value calculated by MER.

Thus, when the amount of noise added to the signal is greater than “B”, the amount of noise calculated by the inter-code distance calculation / accumulation processing unit 152 does not match the amount of noise added to the signal. In particular, when the noise amount is from “B” to “C”, the calculation result of the noise amount shows that the noise amount is decreasing, although the noise amount actually added to the signal increases. can get. For this reason, in the inter-code distance calculation / accumulation processing unit 152, when the data used for generating the “mapping point information” includes an error, the “symbol point closest to the“ received OFDM symbol point ”and the“ reception point ”are received. A value obtained by correcting the “Euclidean distance from the“ OFDM symbol point ”is corrected.

In the correction method, when the noise amount in FIG. 7 is “B”, the difference between the accumulated value of the Euclidean distance calculated by the inter-code distance calculation / accumulation processing unit 152 and the MER value is calculated in advance. It is conceivable to correct the accumulated value of the Euclidean distance calculated by the inter-distance calculation / accumulation processing unit 152. When the difference between the calculated Euclidean distance accumulated value and the MER value is Nd, the inter-code distance calculation / accumulation processing unit 152 applies the error to the signal whose error could not be corrected by the first RS decoding processing unit 135. Averages the value obtained by subtracting Nd from the “Euclidean distance between the“ symbol point closest to the received OFDM symbol point ”and the“ received OFDM symbol point ”, which is the MER value calculation source, and estimates the noise amount To do. As a result, in the first RS decoding processing unit 135, the meanings of the calculation results of the noise amount when error correction is possible and when error correction is impossible can be made substantially equal.

By the way, the Euclidean distance calculated according to the “mapping point error presence / absence information” as described above is calculated in units of OFDM carriers. Then, it is integrated a certain number of times in the symbol direction. For example, the number of integrations may be the same as the longest time of time interleaving performed by the deinterleave processing unit 121. The longest time interleaving time does not indicate the maximum value of the parameters that can be set among the parameters of the time interleaving length specified in the broadcast standard. For example, in the Mode 3 broadcast signal, the interleaving length parameter I = 2 If there is, it indicates the frame length of one OFDM frame (for 204 OFDM symbols). That is, in the case of Mode 3 and interleave length I = 2, the number of integrations of the Euclidean distance is 204. For example, a larger number of integrations such as 256 may be set.

Then, the inter-code distance calculation / accumulation processing unit 152 outputs the distance information between the “received OFDM symbol point information” and the “mapping point information” integrated in symbol units to the second demapping processing unit 153. To do. In the ISDB-T standard, frequency reordering processing called “intra-segment carrier rotation” is performed within a segment during frequency interleaving processing on the transmission side. The data is rearranged to the same frequency position. On the other hand, if the data location differs depending on the symbol number in other broadcasting systems, etc., consider the data rearrangement process according to the symbol number when performing the integration process for the Euclidean distance in the symbol direction a certain number of times. Then, it is necessary to integrate the Euclidean distance between the complex signal of “mapping point information” calculated for the signals at the same frequency position and the complex signal of “information of received OFDM symbol points”.

Further, the inter-code distance calculation / accumulation processing unit 152 can calculate distance information between “information on received OFDM symbol points” and “information on mapping points” through further detailed processing. Here, the correction procedure of “mapping point information” used for calculating the distance information will be described with reference to FIG. 5 again.

FIG. 5 shows the mapping rule when the carrier modulation scheme is 16QAM. In the 16QAM modulation system, “mapping point information” is calculated from 4-bit data.

If the inter-code distance calculation / accumulation processing unit 152 determines that all of the “mapping point error presence / absence information” indicates “no error”, the mapping point is uniquely determined according to FIG. Is the value obtained from the mapping processing unit 151.

Next, when the inter-code distance calculation / accumulation processing unit 152 determines from the “mapping point error presence / absence information” that 1-bit data is “possibly containing an error”, first, the bit including the error ( It is determined whether it is included in (b0, b2) or (b1, b3). As shown in FIG. 5, in the 16QAM modulation system, the real part of the mapping point is uniquely determined from (b0, b2) and the imaginary part is uniquely determined from (b1, b3). On the other hand, since a code point cannot be determined from a pair of bits including an error, a temporary value is assigned.

For example, the inter-code distance calculation / accumulation processing unit 152 may have an error in b0 that is the calculation source of the real part value and b2 is correct information, and the “mapping” obtained from the mapping processing unit 151 The real part of “point information” is replaced with the real part of the code point closest to the real part of “information of received OFDM symbol point”, out of the two code points obtained from b2. The imaginary part of the “mapping point information” is not replaced. Further, the inter-code distance calculation / accumulation processing unit 152 calculates the real part of the “mapping point information” obtained from the mapping processing unit 151 when there is a possibility of an error in b2 and b0 is correct information. , B0, the real part of the code point closest to the real part of the "information on received OFDM symbol points" is replaced. The imaginary part of the “mapping point information” is not replaced.

Further, the inter-code distance calculation / accumulation processing unit 152 may have an error in b1 that is the source of calculation of the imaginary part value, and b3 is correct information, and the “mapping” obtained from the mapping processing unit 151 is obtained. The imaginary part of the "point information" is replaced with the imaginary part of the code point closest to the imaginary part of the "received OFDM symbol point information" among the two code points obtained from b3. The real part of “mapping point information” is not replaced. Further, the inter-code distance calculation / accumulation processing unit 152 calculates the imaginary part of the “mapping point information” obtained from the mapping processing unit 151 when there is a possibility of error in b3 and b1 is correct information. , B1 is replaced with the imaginary part of the code point closest to the imaginary part of “information of received OFDM symbol point”. The real part of “mapping point information” is not replaced.

If it is determined from the “mapping point error presence / absence information” that the 2-bit data is “possibly containing an error”, one error bit exists for each of the pairs (b0, b2) and (b1, b3). It is conceivable that a 2-bit error is biased to one of the pair (b0, b2) or (b1, b3). Of these, in the former case, the real part and the imaginary part of the “mapping point information” are replaced by the same procedure as in the case where only one bit of the above four bits contains an error.

On the other hand, if the inter-code distance calculation / accumulation processing unit 152 determines that 2-bit errors are concentrated on (b0, b2) based on the “mapping point error presence / absence information”, the “mapping” obtained from the mapping processing unit 151 The real part of “point information” is replaced with the real part of the code point closest to the real part of “received OFDM symbol point information”. The imaginary part of the “mapping point information” is not replaced. If the inter-code distance calculation / accumulation processing unit 152 determines from the “mapping point error presence / absence information” that the 2-bit errors are concentrated on (b1, b3), the “mapping point error information” obtained from the mapping processing unit 151 The imaginary part of “information” is replaced with the imaginary part of the symbol point closest to the imaginary part of “information on received OFDM symbol points”. The real part of “mapping point information” is not replaced.

If there is a possibility that 3 bits out of 4 bits of data or all 4 bits of data contain errors from the “mapping point error presence / absence information”, the “mapping point The replacement of the real part and the imaginary part of "information" is performed according to the above-described procedure.

Through the above processing, the intersymbol distance calculation / accumulation processing unit 152 indicates that the “mapping point error presence / absence information” indicates that all the errors have been corrected, In other cases, the Euclidean distance between the corrected “mapping point information” and the “received OFDM symbol point information” is calculated for each OFDM carrier, and is further integrated a certain number of times in the symbol direction. Then, the inter-code distance / accumulation processing unit 152 outputs the distance information between “received OFDM symbol point information” and “mapping point information” integrated in symbol units to the second demapping processing unit 153. .

Hereinafter, distance information between “received OFDM symbol point information” and “mapping point information” integrated in symbol units calculated by the inter-code distance calculation / accumulation processing unit 152 is referred to as “carrier-based interference information”. .

In the above description, the carrier modulation method is described as the 16QAM modulation method. However, when the carrier modulation method is a modulation method including multi-value information, such as 64QAM, the combination of data error occurrences is different. The same calculation method is adopted by replacing the point closest to “information of received OFDM symbol point” with new “mapping point information” among mapping points calculated from bits without error. be able to.

The inter-code distance calculation / accumulation processing unit 152 also outputs new “mapping point information” to the second demapping processing unit 153 at the subsequent stage, and the second demapping processing unit 153 includes the mapping processing unit. Instead of “mapping point information” input from 151, reliability information may be calculated using new “mapping point information” input from the inter-code distance calculation / accumulation processing unit 152.

By the way, the “interference information in units of carriers” calculated by the inter-code distance calculation / accumulation processing unit 152 is calculated from signals obtained as a result of rearranging the data arrangement order in the frequency and time directions by the deinterleave processing unit 121. Value. When calculating the “interference information for each carrier” in the inter-code distance calculation / accumulation processing unit 152, a memory or the like for integrating and holding the Euclidean distances of transmission / reception signal points is required. When the values are stored, the values of the Euclidean distances of the transmission / reception signal points may be rearranged according to the frequency interleaving processing procedure at the time of signal transmission and stored in the memory.

Then, the “carrier-based interference information” can be rearranged in order from the low-frequency OFDM carrier. For example, when a frequency selective interference signal is superimposed around a specific OFDM carrier of the received signal, A large value is biased toward a certain range of “jamming information per carrier”. In this way, it is possible to determine whether or not the received signal is affected by the frequency selective interference signal from the distribution state in the frequency direction of the “carrier-based interference information”. In addition, the position of the OFDM carrier that is affected by the frequency selective interference signal can be identified more accurately. It is also possible to interpolate or blunt the result of “interference information per carrier” or “subject interference information per carrier” when the number of integrations when calculating “interference information per carrier” is small. .

In addition, it may be possible to separately use information on the frequency of the frequency selective interference signal. For example, it is conceivable to calculate a frequency range to be cut off by a filter when a notch filter process for removing an interference signal is performed on a signal upstream of the FFT processing unit.

In addition, as described above, when the data arrangement is changed at the time of calculating the “carrier-based interference information”, the second demapping processing unit 153 at the subsequent stage uses the “carrier-based interference information”. Then, it is necessary to rearrange the “jamming information per carrier” again so that the data and the “jamming information per carrier” are generated from the same carrier position. In the second embodiment, which will be described later, the inter-code distance calculation / accumulation processing unit 152 transmits the “carrier-based interference information” to the first demapping processing unit 122A corresponding to the first demapping processing unit 122. However, the same processing needs to be performed on the first demapping processing unit 122A.

The second demapping processing unit 153 obtains “received OFDM symbol point information” and a data string of the estimation result of the transmission path characteristics from the deinterleaving processing unit 121, and “mapping point information” from the mapping processing unit 151. And “mapping point error presence / absence information” from the inter-symbol distance calculation / accumulation processing unit 152, which is integrated on a symbol-by-symbol basis, information on the distance between “received OFDM symbol point information” and “mapping point information” Get unit interference information). Then, the second demapping processing unit 153 performs demapping processing according to the carrier modulation scheme of each layer included in the control information acquired by the TMCC decoding processing unit 113. However, since the second demapping processing unit 153 processes the data after the error correction processing is performed once, the second demapping processing unit 153 switches the processing method depending on whether or not the data may contain an error.

The second demapping processing unit 153 determines, based on the “mapping point error presence / absence information”, whether or not the data from which the “mapping point information” is calculated may have an error. When there is no possibility of an error, the second demapping processing unit 153 uses “mapping point information” from the mapping processing unit 151 and “received OFDM symbol point” from the deinterleaving processing unit 121 as mapping point information. After obtaining the processing information and selecting the “processing point”, the “mapping point information” is selected as the code point, and the value of the estimation result of the transmission path characteristics is given a large value. The large value is given as “1”, for example, assuming that the magnitude of the transmission line characteristic when there is no amplitude fluctuation in the transmission line is “1”.

On the other hand, when there is a possibility that the data from which the “mapping point information” is calculated has an error, the second demapping processing unit 153 uses the “received OFDM symbol point information” to calculate the reliability information. The information of the estimation result of the transmission path characteristics used is the magnitude of the estimation result of the transmission path characteristics obtained from the deinterleave processing unit 121 (the magnitude of the estimation result of the transmission path characteristics H (ω) calculated for each carrier) and To do. At this time, the “mapping point information” newly generated by the intersymbol distance calculation / accumulation processing unit 152 is used as the information of the reception symbol points used for the calculation of the reliability information, and then the size of the transmission path characteristics May be a value obtained from the deinterleave processing unit 121.

Then, the second demapping processing unit 153 determines whether or not there is a possibility that the data from which the “mapping point information” is calculated has an error. The processing unit 153 uses distance information (interference information in carrier units) between “information on received OFDM symbol points” and “information on mapping points” integrated in symbol units by the inter-code distance calculation / accumulation processing unit 152. Then, the reliability information value calculated from the “information of received OFDM symbol point” and the size of the transmission path characteristic is corrected. By the way, the distance information between “received OFDM symbol point information” and “mapping point information” integrated in symbol units calculated by the inter-code distance calculation / accumulation processing unit 152 is calculated as “mapping point information”. Since the data used in the calculation is calculated from the error-corrected data, the same transmission signal point as the signal generated by the signal transmission station is compared with the reception point obtained as a result of the demodulation process, The Euclidean distance of the signal points can be regarded as a value obtained by integrating the same data carrier for a certain period of time.

Since “jamming information per carrier” can be regarded as a result of more accurately averaging the amount of jamming signals contained in each carrier in the time direction, the reliability information of each received data is corrected using “jamming information per carrier”. To do. Specifically, it is calculated from received symbol points and transmission path characteristics so that the reliability of data carriers with a large “carrier interference information” is low and the reliability of data carriers with a small “carrier interference information” is high. The reliability information value is divided by “jamming information per carrier”. In addition, a carrier that always indicates that the “mapping point error presence / absence information” is an error, or that “carrier-based interference information” is prominently large, sets the reliability information value to “0”, The data contained in the carrier may not be trusted at all.

Then, the second demapping processing unit 153 outputs the generated bit data and reliability information to the second bit deinterleaving processing unit 161 in the second error correction unit 160.

Furthermore, as described above, the second demapping processing unit 153 obtains “interference information per carrier” from the inter-code distance calculation / accumulation processing unit 152. By averaging the “jamming information for each carrier” in the carrier direction, it can be used separately as an indicator of the amount of jamming signals included in the received signal. If the C / N of the received OFDM signal fluctuates so that the signal level changes in a short time, the second demapping processing unit uses the average value of the interference information for each carrier as the noise amount of the received signal. The reliability information output from 153 to the second bit deinterleave processing unit 161 in the second error correction unit 160 may be further corrected. It can also be used as a signal quality value of a signal received by the multicarrier modulation signal receiving apparatus separately.

Furthermore, the following measures can be taken as the signal quality value of the received signal. Since the “information on received OFDM symbol points” obtained by the inter-code distance calculation / accumulation processing unit 152 is a value that has passed through the deinterleaving processing unit 121, the memory amount of the deinterleaving processing unit 121 is reduced. It is conceivable that the bit width is limited by quantization. As a result, when the signal quality is high, it is difficult to calculate the signal quality index value with high accuracy in the processing block subsequent to the deinterleave processing unit 121 due to the influence of the quantization error. On the other hand, if the MER value is calculated for the output signal of the equalization processing unit 113 before the deinterleaving processing unit 121 and the signal quality is higher than a certain value, the deinterleaving processing unit 121 If the value calculated in the previous stage is used as the signal quality index value and the signal quality is lower than a certain value, the “interference information per carrier” obtained from the inter-code distance calculation / accumulation processing unit 152 is used in the carrier direction. The averaged value is used as the signal quality index value.

The second error correction unit 160 performs error correction processing based on the bit data and reliability information obtained from the second demapping processing unit 153, and generates an original signal sequence. Hereinafter, the operation of the second error correction unit 160 will be described in detail with reference to FIG.

The second bit deinterleave processing unit 161 rearranges the bit data and reliability information obtained from the second demapping processing unit 153 into the original order in accordance with the ISDB-T standard, and rearranges the bit data. And the reliability information are output to the second decoding processing unit 162.

The second decoding processing unit 162 obtains bit data and reliability information from the second bit deinterleaving processing unit 161. The second decoding processing unit 162 is a second bit deinterleaving processing unit according to the coding rate of the inner code of each layer (coding rate of the convolutional code) included in the control information acquired by the TMCC decoding processing unit 113 A dummy bit is inserted into the bit position thinned out on the transmission side with respect to the data string of bit data obtained from 131, and the value is undefined. The second decoding processing unit 162 performs decoding processing by weighting the received bit data according to the reliability information. Currently, a decoding process called Viterbi decoding is widely used, but a process according to another decoding algorithm may be used. The second decoding processing unit 162 outputs the decoding result data string to the second byte deinterleaving processing unit 163.

The second byte deinterleave processing unit 163 receives the data sequence of the decoding result from the second decoding processing unit 162, rearranges the received data sequence of the decoding result into the original order in accordance with the ISDB-T standard, The rearranged data string is output to the second energy despreading processing unit 164.

The second energy spreading processing unit 164 restores the energy spreading processing performed on the signal transmission side according to the ISDB-T standard for the data string obtained from the second byte deinterleaving processing unit 163. And the converted data string is output to the second RS decoding processing unit 165.

The second RS decoding processing unit 165 receives the data string from the second energy spreading processing unit 164, performs Reed-Solomon decoding processing using the assigned outer code, and performs a Reed-Solomon decoded transport stream The data string of the packet is output to the TS reproduction processing unit 171.

The TS reproduction processing unit 171 obtains the data sequence after Reed-Solomon decoding from the second RS decoding processing unit 165, and in order to make the number of packets of the transport stream constant regardless of the transmission parameters, an appropriate number of Complement processing is performed on the null packet, and the packet data of the transport stream after supplementing the null packet is output to the TS decode processing unit 172.

The TS decode processing unit 172 obtains the transport stream packet output from the TS playback processing unit 171, and based on the information included in the transport stream, a video packet, an audio packet, and a PCR (Program Clock Reference) packet Are output to the MPEG decoding processing unit 173.

The MPEG decoding processing unit 173 includes a video decoder and an audio decoder. The video decoder extracts video packets from the transport stream packets obtained from the TS decoding processing unit 172, decodes the data, and generates image data. The audio decoder extracts an audio packet from the transport stream obtained from the TS decoding processing unit 172, decodes the data, and generates audio data.

Then, the MPEG decode processing unit 173 adjusts the output timing of the image data and the audio data based on the time information included in the PCR packet, and then outputs the image data and the audio data to a display device or the like.

Through the above processing, the multicarrier modulation signal receiving apparatus according to the first embodiment restores the transmission signal point generated at the signal transmission station from the data resulting from the error correction processing once, and demodulates the transmission signal point and the demodulation. The received signal point obtained from the unit is compared in units of carriers, and a value obtained by integrating the Euclidean distance obtained from the comparison result for a certain period of time is regarded as an interference signal amount included in each carrier and transmitted to the second error correction unit 160 Sex information can be corrected. For this reason, it is possible to obtain high reception performance as compared with the conventional method. In particular, when the received signal is affected by a frequency-selective interference signal, it is possible to more accurately calculate the amount of interference signal that is biased in units of carriers, so that a high effect can be obtained.

By the way, in the description of the configuration of the multicarrier modulation signal receiving apparatus of the first embodiment described above, for example, the processing timing is adjusted for each layer as the signal is transmitted by a different carrier modulation method for each layer. Although all procedures are not necessarily described for the processing specified in the ISDB-T standard, processing according to the ISDB-T standard is performed in an appropriate block unless otherwise specified.

In the first embodiment, the error correction process is performed once in the second error correction unit 160 from the encoding unit 140 and output to the TS reproduction processing unit 171 as shown in FIG. The second error correction unit 160 may perform error correction processing a plurality of times from the unit 140 and output to the TS reproduction processing unit 171. In this case, as shown in FIG. 8, in order to count the number of times of error correction processing in the second error correction unit 160, an error correction count unit 166 for inputting the output signal of the second error correction unit 160 is provided. . For example, when the number of repetitions is 2, the error correction count unit 166 outputs a signal to the encoding unit 140 when the number of error correction processes in the second error correction unit 160 is 1, and error correction is performed. When the number of processes is two, the data is output to the TS reproduction processing unit 171. Further, for example, the signal processing from the error correction count unit 166 to the encoding unit 140 is repeated a plurality of times within the range where the operation speed of the second error correction processing unit 160 is increased and the output signal output time is not delayed, It is also possible to increase the error correction effect.

In the first embodiment, two blocks that perform the same processing are provided as in the first decoding processing unit 132 and the second decoding processing unit 162 as shown in FIG. 2, but may be shared. . In this case, as shown in FIG. 9, the output signal from the second demapping processing unit 153 is input to the first error correction unit 130. In order to count how many times the error correction processing in the first error correction unit 130 is performed, an error correction count unit 136 for inputting an output signal of the first error correction unit 130 is provided. Then, the error correction count unit 136 outputs a signal to the encoding unit 140 when the number of error correction processes in the first error correction unit 130 is one, and the number of error correction processes reaches a specified number. A signal is output to the TS reproduction processing unit 171. In addition, for example, the operation speed of the first error correction processing unit 130 is set high, and the delay from the output time of the output signal does not increase so that the second demapping processing unit 153 transfers to the first error correction unit 130. It is also possible to increase the error correction effect by repeating this signal processing a plurality of times.

(Embodiment 2)
Embodiment 2 of the present invention will be described below with reference to the drawings. In the second embodiment, components that perform substantially the same processing as the components in the first embodiment are denoted by the same reference numerals, and the description thereof can be applied. Omit or keep a simple description.

FIG. 10 is a block diagram showing a configuration of the multicarrier modulation signal receiving apparatus according to the second embodiment, and FIG. 11 is a block diagram showing a detailed configuration of the multicarrier modulation signal receiving apparatus of FIG.

As shown in FIG. 10, the multicarrier modulation signal receiving apparatus according to the second embodiment includes an antenna unit 101, a tuner unit 102, an A / D conversion processing unit 103, a demodulation unit 110, and a deinterleaving processing unit 121. The first demapping processing unit 122A, the first error correction unit 130, the encoding unit 140, the mapping processing unit 151, the inter-code distance calculation / accumulation processing unit 152, and the second demapping processing. Section 153, second error correction section 160, TS (Transport Stream: transport stream) reproduction processing section 171, TS decoding processing section 172, and MPEG (Moving Picture Experts Group) decoding processing section 173. ing.

As shown in FIG. 11, the demodulation unit 110 in FIG. 10 includes an orthogonal detection processing unit 111, an FFT processing unit 112, and an equalization processing unit 113. Further, as shown in FIG. 11, the first error correction unit 130 of FIG. 10 includes a first bit deinterleaving processing unit 131, a first decoding processing unit 132, and a first byte deinterleaving processing unit 133. And a first energy despreading processing unit 134 and a first RS decoding processing unit 135. Further, as shown in FIG. 11, the encoding unit 140 in FIG. 10 includes an RS code processing unit 141, an error information addition processing unit 142, an energy spread processing unit 143, a byte interleave processing unit 144, and a convolutional code processing. 145, error information calculation processing unit 146, and bit interleaving processing unit 147. Further, as shown in FIG. 11, the second error correction unit 160 in FIG. 10 includes a second bit deinterleaving processing unit 161, a second decoding processing unit 162, and a second byte deinterleaving processing unit 163. And a second energy despreading processing unit 164 and a second RS decoding processing unit 165.

Next, the configuration of the multicarrier modulation signal receiving apparatus in the second embodiment in FIGS. 10 and 11 is compared with the configuration of the multicarrier modulation signal receiving apparatus in the first embodiment in FIGS.

Compared with the multicarrier modulation signal receiving apparatus in the first embodiment, the multicarrier modulation signal receiving apparatus in the second embodiment is such that the inter-code distance calculation / accumulation processing unit 152 sets the “carrier-based interference information” to the second value. Output to the first demapping processing unit 122A in addition to the demapping processing unit 153, and the first demapping processing unit 122A performs demapping processing also using “carrier-based interference information”. Yes.

The first demapping processing unit 122A obtains the “received OFDM symbol points” rearranged from the deinterleaving processing unit 121 and the data string of the estimation result of the transmission path characteristics. The first demapping processing unit 122A regards the mapping point closest to the “received OFDM symbol point” as the transmission signal point according to the carrier modulation scheme of each layer included in the control information acquired by the TMCC decoding processing unit 113. , Generate bit data. In addition, the first demapping processing unit 122A performs distance information between the “received OFDM symbol point” and the mapping point (transmission signal point) closest to the “received OFDM symbol point” (“distance information of the received symbol point”). ) And the information of the data string of the estimation result of the transmission path characteristics obtained separately from the deinterleave processing unit 121 and the “interference information per carrier” obtained from the inter-symbol distance calculation / accumulation processing unit 152 in combination. Generate sex information. Then, the first demapping processing unit 122A outputs the generated bit data and reliability information to the first bit deinterleaving processing unit 131 in the first error correction unit 130.

Here, a method of generating reliability information in the first demapping processing unit 122A will be described. The first demapping processing unit 122A generates information for performing error correction processing called soft decision in the first decoding processing unit 132 in the subsequent stage. First, the first demapping processing unit 122A obtains a data string of “received OFDM symbol points” and “estimation results of transmission path characteristics” after the deinterleaving processing from the deinterleaving processing unit 121. Then, the first demapping processing unit 122A regards the mapping point closest to the “received OFDM symbol point” as the transmission signal point, and calculates the data of the complex signal point of the closest mapping point. Then, the first demapping processing unit 122A converts the complex signal into a bit string according to the complex signal point and information bit allocation rule as shown in FIG. And a bit data string are output.

Further, the first demapping processing unit 122A performs “distance information of received symbol points”, “data string of transmission path characteristic estimation results” obtained from the deinterleaving processing unit 121, and inter-code distance calculation / accumulation. The reliability information is generated by combining the “interference information in units of carriers” obtained from the processing unit 152. The reliability information generated by the first demapping processing unit 122 is also called likelihood, and is a value indicating 1-likeness and 0-likeness of data in bit units. For example, when there is a high possibility that a certain bit is 1, a positive value is given as the value of reliability information, and when there is a high possibility that a certain bit is 0, a negative value is given. If a bit has the same probability of 1 and 0, 0 is given. Also, the higher the reliability, the larger the absolute value. Thereby, in an error correction process by a Viterbi decoder or the like, a decoding process is performed on a code string transmitted based on the zeroness and the oneness of the input bit string.

By the way, as the cause of error in the received signal of the OFDM signal, if the fluctuation of the transmission path characteristics between transmission and reception and the amount of thermal noise inside the tuner with respect to the received signal level are considered to be main, the reliability value is as follows: Can be calculated.

First, the influence of the transmission path characteristics between the former transmission and reception is divided in two: transmission path estimation error due to transmission path fluctuation (fading) and signal attenuation between transmission and reception (including multipath attenuation for a specific carrier) and It can be divided into two. Considering the case where the receiving antenna is fixed, the reliability value of the demodulated signal can be calculated from the estimated value of signal attenuation per OFDM carrier between transmission and reception. For each OFDM symbol, the size (for example, the square value) of the estimated value H (ω) of the transmission path characteristic used for the division of the received signal by the equalization processing unit 113 is calculated. By obtaining the data string, it is possible to obtain an estimated value of signal attenuation in OFDM carrier units.

As for transmission path estimation errors due to transmission path fluctuations, assuming mobile reception such as cars, the effects of transmission path estimation errors due to transmission path fluctuations cannot be ignored, but the transmission path characteristics estimated from pilot signals The estimation error can be reduced by devising the interpolation processing method, and the transmission path estimation error can be further reduced by using a technique for estimating / removing the amount of intercarrier interference called ICI (Inter Carrier Interference).

The amount of thermal noise inside the latter tuner can be estimated from the C / N amount of the entire OFDM signal band, assuming that the thermal noise generated inside the tuner is white noise and follows Gaussian characteristics. This can be replaced by a value obtained by integrating the “reception symbol point distance information” in the carrier direction.

In other words, the reliability information value for each bit data is the size of the transmission path characteristics in units of OFDM carriers, considering fluctuations in transmission path characteristics between transmission and reception and the influence of the amount of thermal noise inside the tuner on the received signal level. The value of the reliability information may be given so as to be proportional and inversely proportional to the noise amount of the entire signal (proportional to the C / N amount).

Further, considering the case where a reception error occurs due to the frequency selective interference signal other than the thermal noise inside the tuner, the reliability value calculated as described above is further calculated by the inter-code distance calculation / accumulation processing unit 152. What is necessary is just to correct | amend according to the "jamming information per carrier" calculated per OFDM carrier. If the “carrier-based interference information” is large, the reliability value is corrected to be low or the reliability value is set to “0”. The procedure for correcting the reliability value is in accordance with the correction method conventionally performed by the MER value. However, the “interference information for each carrier” is “mapping point information” generated again from the code corrected by the error correction process. In the case of the Euclidean distance with “information of received OFDM symbol points”, the value directly indicates the magnitude of the interference added to the carrier, and therefore the reliability value is corrected by a more accurate interference signal amount. Is possible.

However, not all data affected by the interference signal can be error-corrected, and the Euclidean distance between the "mapping point information" and the "received OFDM symbol point information" is accumulated in the time direction for a fixed number of carriers. This value is used as “carrier-based interference information”. Note that the first demapping processing unit 122A determines that the “symbol point closest to the received OFDM symbol point” until “interference information per carrier” is calculated by the inter-code distance calculation / accumulation processing unit 152. The reliability value may be corrected using the MER value obtained by integrating the Euclidean distance from the “received OFDM symbol point”. In addition, a carrier that always indicates that the “mapping point error presence / absence information” is an error, or that “carrier-based interference information” is prominently large, sets the reliability information value to “0”, The data contained in the carrier may not be trusted at all.

Through the above processing, the multicarrier modulation signal receiving apparatus according to the second embodiment restores the transmission signal point generated at the signal transmission station from the data resulting from the error correction processing once, and demodulates the transmission signal point and the demodulation. The received signal points obtained from the unit are compared in carrier units, and the value obtained by integrating the Euclidean distance obtained from the comparison result for a certain period of time is regarded as the amount of interfering signals included in each carrier and the reliability information transmitted to the error correction unit is corrected. Therefore, it is possible to obtain higher reception performance as compared with the conventional method. In particular, when the received signal is affected by a frequency-selective interference signal, it is possible to more accurately calculate the amount of interference signal that is biased in units of carriers, so that a high effect can be obtained.

In the second embodiment, the error correction process is performed once by the second error correction unit 160 from the encoding unit 140 and output to the TS reproduction processing unit 171 as shown in FIG. The second error correction unit 160 may perform error correction processing a plurality of times from the unit 140 and output to the TS reproduction processing unit 171. In this case, as shown in FIG. 12, in order to count the number of times of error correction processing in the second error correction unit 160, an error correction count unit 166 for inputting the output signal of the second error correction unit 160 is provided. . For example, when the number of repetitions is 2, the error correction count unit 166 outputs a signal to the encoding unit 140 when the number of error correction processes in the second error correction unit 160 is 1, and error correction is performed. When the number of processes is two, the data is output to the TS reproduction processing unit 171. Further, for example, the signal processing from the error correction count unit 166 to the encoding unit 140 is repeated a plurality of times within the range where the operation speed of the second error correction processing unit 160 is increased and the output signal output time is not delayed, It is also possible to increase the error correction effect.

In the second embodiment, as shown in FIG. 11, two blocks that perform the same processing are provided, such as the first decoding processing unit 132 and the second decoding processing unit 162, but they may be shared. . In this case, as shown in FIG. 13, the output signal from the second demapping processing unit 153 is input to the first error correction unit 130. In order to count how many times the error correction processing in the first error correction unit 130 is performed, an error correction count unit 136 for inputting an output signal of the first error correction unit 130 is provided. Then, the error correction count unit 136 outputs a signal to the encoding unit 140 when the number of error correction processes in the first error correction unit 130 is one, and the number of error correction processes reaches a specified number. A signal is output to the TS reproduction processing unit 171. In addition, for example, the operation speed of the first error correction processing unit 130 is set high, and the delay from the output time of the output signal does not increase so that the second demapping processing unit 153 transfers to the first error correction unit 130. It is also possible to increase the error correction effect by repeating this signal processing a plurality of times.

All or some of the components other than the antenna unit 101 of the multicarrier modulation signal receiving apparatus described in the first and second embodiments may be realized by an LSI that is an integrated circuit. At this time, all or a part of the constituent elements may be individually made into one chip, or may be made into one chip so as to include a part or all. Further, although it is referred to as LSI here, it may be referred to as IC, system LSI, super LSI, or ultra LSI depending on the degree of integration. Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. Further, the method of circuit integration is not limited to LSI, but may be realized by a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array) or a reconfigurable processor capable of reconfiguring connection and setting of circuit cells inside the LSI may be used. Furthermore, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Possible applications include biotechnology.

The present invention can be used for a multicarrier modulation signal receiving apparatus and an integrated circuit that receive a received signal that is affected by a frequency selective interference signal.

DESCRIPTION OF SYMBOLS 101 Antenna part 102 Tuner part 103 A / D conversion process part 110 Demodulation part 111 Orthogonal detection process part 112 FFT process part 113 Equalization process part 121 Deinterleave process part 122,122A 1st demapping process part 130 1st error Correction unit 131 First bit deinterleave processing unit 132 First decoding processing unit 133 First byte deinterleaving processing unit 134 First energy spread processing unit 135 First RS decoding processing unit 136 Error correction counting unit 140 Code Conversion unit 141 RS code processing unit 142 error information addition processing unit 143 energy spread processing unit 144 byte interleave processing unit 145 convolutional code processing unit 146 error information calculation processing unit 147 bit interleave processing unit 151 mapping processing unit 152 inter-code distance calculation / accumulation Processing Unit 153 Second Demapping Processing Unit 160 Second Error Correction Unit 161 Second Bit Deinterleaving Processing Unit 162 Second Decoding Processing Unit 163 Second Byte Deinterleaving Processing Unit 164 Second Energy Despreading Processing Unit 165 second RS decoding processing unit 166 error correction counting unit 171 TS reproduction processing unit 172 TS decoding processing unit 173 MPEG decoding processing unit

Claims

A demodulator that demodulates a multi-carrier modulation signal and generates a data sequence of estimation results of received symbol points and transmission path characteristics for each carrier;
A deinterleaving processing unit for rearranging a data sequence of estimation results of reception symbol points and transmission path characteristics input from the demodulation unit;
A first demapping processing unit that generates bit data and reliability information of the bit data from a rearranged received symbol point input from the deinterleave processing unit and a data sequence of estimation results of transmission path characteristics;
A first error correction unit that performs error correction processing based on reliability information of bit data input from the first demapping processing unit and generates data in which a transmission signal sequence is restored;
An error for performing an encoding process on the data restored from the transmission signal sequence input from the first error correction unit and determining whether the data after the encoding process has been generated from data that could not be error-corrected An encoding unit that generates a signal indicating a correctable range;
The data that has been subjected to the encoding process input from the encoding unit is divided in accordance with a carrier modulation scheme and then mapped to generate mapping point information, and one or more calculation sources of the mapping point information A mapping processing unit that generates error presence / absence information of a mapping point from a signal indicating an error-correctable range corresponding to each of the data;
Based on the rearranged received symbol points input from the deinterleave processing unit, mapping point information and mapping point error presence / absence information input from the mapping processing unit, the received symbol points and the mapping points An inter-code distance calculation / accumulation processing unit that calculates the distance to the information of
Reordered received symbol points input from the deinterleave processing unit and data string of transmission path characteristic estimation results, mapping point information input from the mapping processing unit and mapping point error presence / absence information, and between the codes A second demapping processing unit that generates bit data and reliability information of the bit data from distance information between the received symbol point and the mapping point information input from a distance calculation / accumulation processing unit;
A second error correction unit that performs error correction processing based on the bit data and reliability information input from the second demapping processing unit, and generates an original signal sequence;
A multi-carrier modulation signal receiving apparatus comprising:
The second demapping processing unit
Based on error presence / absence information of mapping point information input from the mapping processing unit, rearranged received symbol points input from the deinterleaving processing unit, mapping point information input from the mapping processing unit, The multicarrier modulation signal receiving apparatus according to claim 1, wherein the reliability information is generated by generating a new signal point from.
The inter-code distance calculation / accumulation processing unit
Based on the error presence / absence information of the mapping point input from the mapping processing unit,
When it is determined that the mapping point information input from the mapping processing unit is generated only from data that has been error-corrected, the rearranged received symbol points input from the deinterleaving processing unit, and the mapping processing The Euclidean distance with the mapping point information input from the
When it is determined that the mapping point information input from the mapping processing unit is generated only from data that could not be error-corrected, the rearranged received symbol points input from the deinterleaving processing unit and the reception The Euclidean distance from the symbol point to the nearest transmission signal point is integrated in carrier units,
When it is determined that the mapping point information input from the mapping processing unit is generated from data that has been error-corrected and data that has not been error-corrected, among the code points determined from the data that has been error-corrected The code point closest to the rearranged received symbol point input from the deinterleave processing unit is regarded as the transmission signal point, the rearranged received symbol point input from the deinterleave processing unit, and the transmission signal point Accumulate Euclidean distance from the regarded code point in carrier units,
The multicarrier modulation signal receiving apparatus according to claim 2, wherein an integration result is output as a distance between the reception symbol point and the mapping point information.
The inter-code distance calculation / accumulation processing unit
Reordered received symbols input from the deinterleave processing unit when it is determined that mapping point information input from the mapping processing unit is generated from data that has been error-corrected and data that has not been error-corrected The multicarrier modulation signal according to claim 3, wherein correction is performed so that a Euclidean distance between a point and a code point regarded as the transmission signal point is small, and the corrected Euclidean distance is integrated in units of carriers. Receiver device.
Error correction that counts the number of error correction processes performed in the second error correction unit and outputs the output of the second error correction unit to the encoding unit when the number of error correction processes is less than a predetermined number The multicarrier modulation signal receiving apparatus according to claim 1, further comprising a counting unit.
The first demapping processing unit further generates the reliability information by using distance information between the received symbol point and the mapping point information input from the inter-code distance calculation / accumulation processing unit. The multicarrier modulation signal receiver according to claim 1, wherein
The second demapping processing unit
Based on error presence / absence information of mapping point information input from the mapping processing unit, rearranged received symbol points input from the deinterleaving processing unit, mapping point information input from the mapping processing unit, The multicarrier modulation signal receiving apparatus according to claim 6, wherein a new signal point is generated from the signal to generate the reliability information.
The inter-code distance calculation / accumulation processing unit
Based on the error presence / absence information of the mapping point input from the mapping processing unit,
When it is determined that the mapping point information input from the mapping processing unit is generated only from data that has been error-corrected, the rearranged received symbol points input from the deinterleaving processing unit, and the mapping processing The Euclidean distance with the mapping point information input from the
When it is determined that the mapping point information input from the mapping processing unit is generated only from data that could not be error-corrected, the rearranged received symbol points input from the deinterleaving processing unit and the reception The Euclidean distance from the symbol point to the nearest transmission signal point is integrated in carrier units,
When it is determined that the mapping point information input from the mapping processing unit is generated from data that has been error-corrected and data that has not been error-corrected, among the code points determined from the data that has been error-corrected The code point closest to the rearranged received symbol point input from the deinterleave processing unit is regarded as the transmission signal point, the rearranged received symbol point input from the deinterleave processing unit, and the transmission signal point Accumulate Euclidean distance from the regarded code point in carrier units,
The multicarrier modulation signal receiving apparatus according to claim 7, wherein an integration result is output as a distance between the received symbol point and the mapping point information.
The inter-code distance calculation / accumulation processing unit
Reordered received symbols input from the deinterleave processing unit when it is determined that mapping point information input from the mapping processing unit is generated from data that has been error-corrected and data that has not been error-corrected The multicarrier modulation signal according to claim 8, wherein correction is performed so that a Euclidean distance between a point and a code point regarded as the transmission signal point is small, and the corrected Euclidean distance is integrated in a carrier unit. Receiver device.
Error correction that counts the number of error correction processes performed in the second error correction unit and outputs the output of the second error correction unit to the encoding unit when the number of error correction processes is less than a predetermined number The multicarrier modulation signal receiving apparatus according to claim 6, further comprising a counting unit.
A demodulator that demodulates a multi-carrier modulation signal and generates a data sequence of estimation results of received symbol points and transmission path characteristics for each carrier;
A deinterleaving processing unit for rearranging a data sequence of estimation results of reception symbol points and transmission path characteristics input from the demodulation unit;
A first demapping processing unit that generates bit data and reliability information of the bit data from a rearranged received symbol point input from the deinterleave processing unit and a data sequence of estimation results of transmission path characteristics;
A first error correction unit that performs error correction processing and generates data obtained by restoring the transmission signal sequence;
An error for performing an encoding process on data obtained by restoring the transmission signal sequence generated by the first error correction unit and determining whether the data after the encoding process was generated from data that could not be error-corrected An encoding unit that generates a signal indicating a correctable range;
Error correction that counts the number of error correction processes performed by the first error correction unit and outputs the output of the first error correction unit to the encoding unit when the number of error correction processes is less than a predetermined number A counting section;
The data that has been subjected to the encoding process input from the encoding unit is divided in accordance with a carrier modulation scheme and then mapped to generate mapping point information, and one or more calculation sources of the mapping point information A mapping processing unit that generates error presence / absence information of a mapping point from a signal indicating an error-correctable range corresponding to each of the data;
Based on the rearranged received symbol points input from the deinterleave processing unit, mapping point information and mapping point error presence / absence information input from the mapping processing unit, the received symbol points and the mapping points An inter-code distance calculation / accumulation processing unit that calculates the distance to the information of
Reordered received symbol points input from the deinterleave processing unit and data string of transmission path characteristic estimation results, mapping point information input from the mapping processing unit and mapping point error presence / absence information, and between the codes Generate bit data and reliability information of the bit data from the distance information between the received symbol point and the mapping point information input from the distance calculation / accumulation processing unit and output to the first error correction unit A second demapping processing unit,
With
The first error correction unit performs error correction processing based on reliability information of bit data input from the first demapping processing unit, generates data in which a transmission signal sequence is restored, and generates the second data An error correction process is performed based on bit data input from the demapping processing unit 153 and reliability information of the bit data.
The first demapping processing unit further generates the reliability information by using distance information between the received symbol point and the mapping point information input from the inter-code distance calculation / accumulation processing unit. The multicarrier modulation signal receiving apparatus according to claim 11, which is performed.
A demodulation circuit that demodulates a multicarrier modulation signal and generates a data sequence of estimation results of reception symbol points and transmission path characteristics for each carrier;
A deinterleave processing circuit for rearranging a data sequence of estimation results of reception symbol points and transmission path characteristics input from the demodulation circuit;
A first demapping processing circuit that generates bit data and reliability information of the bit data from a rearranged received symbol point input from the deinterleave processing circuit and a data string of estimation results of transmission path characteristics;
A first error correction circuit for performing error correction processing based on reliability information of bit data input from the first demapping processing circuit and generating data obtained by restoring a transmission signal sequence;
An error for performing an encoding process on the data restored from the transmission signal sequence input from the first error correction circuit and for determining whether the data after the encoding process is generated from the data that could not be error-corrected An encoding circuit for generating a signal indicating a correctable range;
The data that has been subjected to the encoding process input from the encoding circuit is divided in accordance with a carrier modulation scheme, and mapping is performed to generate mapping point information, and one or more calculation sources of the mapping point information are calculated A mapping processing circuit that generates error presence / absence information of a mapping point from a signal indicating an error correction possible range corresponding to each of the data;
Based on the rearranged received symbol points inputted from the deinterleave processing circuit, mapping point information inputted from the mapping processing circuit, and mapping point error presence / absence information, the received symbol points and the mapping points Inter-code distance calculation / cumulative processing circuit for calculating the distance to the information of
A rearranged received symbol point input from the deinterleave processing circuit and a data string of transmission path characteristic estimation results, mapping point information input from the mapping processing circuit and mapping point error presence / absence information, and between the codes A second demapping processing circuit for generating bit data and reliability information of the bit data from distance information between the received symbol point and the mapping point information input from a distance calculation / accumulation processing circuit;
A second error correction circuit that performs error correction processing based on the bit data and reliability information input from the second demapping processing circuit and generates an original signal sequence;
An integrated circuit comprising:
The first demapping processing circuit further generates the reliability information by using distance information between the received symbol point and the mapping point information input from the inter-code distance calculation / accumulation processing circuit. 14. An integrated circuit according to claim 13, which is performed.